Available online at www.sciencedirect.com Physica E 17 (2003) 505–506 www.elsevier.com/locate/physe Anti-correlated vertical self-organization of InAs nanowires in stacked structures on InP(0 0 1) with InAlAs spacer layer M. Gendry a ; * , J. Brault a , B. Salem b , G. Bremond b , O. Marty c a LEOM, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully Cedex, France b LPM, INSA de Lyon, Bat 502, 69621 Villeurbanne Cedex, France c LENAC, Universit e Claude Bernard Lyon 1, 69622 Villeurbanne Cedex, France Abstract We address the anti-correlated vertical self-organization of stacked InAs nanowires grown on InP(0 0 1) using InAlAs as spacer layers. Using atomic force microscopy (AFM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy, we show that the lateral and vertical organization of the nanowires can be optimized by considering two main parameters: (i) the InAlAs spacer layer thickness (SLT) and (ii) the arsenic pressure during the InAs layer growth. With an optimal SLT/arsenic pressure combination, the nanowire size homogeneity can be improved, in ten-plane stacked structures with a SLT in the 10 –15 nm range, to achieve PL linewidths as low as 90 meV at 8 K, comparing to the 130 meV linewidth obtained for single-plane structures. ? 2002 Elsevier Science B.V. All rights reserved. PACS: 78.55.Cr; 73.21.La Keywords: Stacked structures; Nanowires; InAs/InAlAs/InP(0 0 1) 1. Introduction Extensive works have been devoted to control- ling the formation of self-organized quantum islands (QIs) by the Stranski–Krastanov (S–K) growth mode of strained layers. This is important for potential ap- plications of optoelectronic devices, such as lasers or photodetectors, using semiconductor QIs as the ac- tive region. In this context, InAs QIs on InAlAs/InP are promising candidates for quantum dot or quan- tum wire infrared photodetectors [1,2]. In order to reduce the QIs size distribution, a widely used approach is to accomplish a stacking process. In such * Corresponding author. Tel.: +33-4-72-18-60-50. E-mail address: michel.gendry@ec-lyon.fr (M. Gendry). InAs/InP stacked structures with an InAlAs spacer layer, we have previously shown that the stacking pro- cess produces well organized InAs nanowires with a remarkable anti-correlated vertical arrangement which is principally the result of a phase separation which takes place in the InAlAs spacer layer [3]. Here, we show that the lateral and vertical self-organization of the nanowires depends on the spacer layer thickness (SLT) and on the arsenic pres- sure during the InAs layer growth. 2. Experiment and results The samples were grown at 525 ◦ C by solid source molecular beam epitaxy on semi-insulating InP(0 0 1) 1386-9477/03/$ - see front matter ? 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S1386-9477(02)00851-2